Such a lighting device, which is known from EP 2009345 A2, comprises a lens having a first optical refractive element arranged around a peripheral edge and a second optical refractive element centrally located on the lens. Between the light source, such as a light emitting diode (LED), and the lens a reflector is located. A forward emitted portion of the light of the LED goes directly to the lens whilst a sideward emitted portion is reflected by the reflector before it goes to the lens.
A disadvantage of this known lighting device is that the perceived luminance of the lens is of the same order as the luminance of the light source. In the case of a high power LED an intense and blinding light will be emitted by the lighting device.
The use of such a lighting device with high power LEDs for general indoor lighting is difficult because of the extreme high luminance of the LED. In order to avoid direct exposure of the observer to the high luminance of the LED, luminance transformers may be added. However, such luminance transformers have the disadvantage that they lead to a decrease of the optical efficiency and an increase of the costs of the lighting device.